The Massachusetts State Building Code consists of a series of international model codes and state-specific amendments adopted by the Board of Building Regulation and Standards (BBRS). The BBRS regularly updates the state building codes as new information and technology becomes available and change is warranted.
The MSBC is separated into two distinct volumes: The Residential volume regulates all one- and two-family structures and townhouses that are three stories or less, as well as their accessory structures; The Base volume regulates all structures that are not covered by the Residential regulations.
The base documents for the MSBC commercial and residential codes are the International Building Code and the International Residential Code. A primary difference between the two is the reliance of the Residential Code on prescriptive requirements related to platform and balloon frame construction of light-frame buildings. This allows designers, contractors and inspectors to rely on simpler proven systems for foundations, walls, floors and roofs as well as piping and ventilation systems rather than requiring a thorough engineering analysis of each individual element of the building.
Throughout the residential code, there are provisions that allow for engineered design where non-conventional structures and systems are proposed or where an element is not conforming to the standard prescriptive criteria. If the performance can be shown through accepted engineering practice to demonstrate compliance, non-standard approaches can be considered. The burden falls upon the design professional to demonstrate to the local jurisdiction how the applicable criteria are being met.